The invention relates to a camshaft adjuster for an internal combustion engine, in which lubrication is performed via a flow of lubricant.
Camshaft adjusters can be roughly classified as follows:
A. Phase adjusters with a control element, that is, a functional unit, which engages in the mass flow or energy flow, for example, hydraulically, electrically, or mechanically, and rotates with gear elements of the camshaft adjuster.
B. Phase adjusters with a separate setting element, that is, a functional unit, in which the control parameter required for the control method of the control element is formed from the controller output parameter, and a separate control element. Here, there are the following structural forms:
a. Phase adjusters with a co-rotating actuator and a co-rotating control element, for example, a step-up ratio gear, whose adjustment shaft can be advanced by a co-rotating hydraulic motor or centrifugal force motor and can be reset by a spring.
b. Phase adjusters with a co-rotating control element and a stationary, engine-fixed actuator, for example, an electric motor or an electrical or mechanical brake, see also DE 100 38 354 A1, DE 102 06 034 A1, EP 1 043 482 B1.
c. Phase adjusters with a direction-dependent combination of solutions according to a. and b., for example, an engine-fixed brake, in which part of the brake power is used for adjustments toward an advanced position, in order to tension a spring, which allows resetting after the brake is deactivated, see also DE 102 24 446 A1, WO 03-098010, US 2003 0226534, DE 103 17 607 A1.
In systems according to B.a. to B.c., actuators and control elements are connected to each other by an adjustment shaft. The connection can be switchable or non-switchable, detachable or non-detachable, lash-free or with lash, and flexible or stiff. Independent of the structural form, the adjustment energy can be realized in the form of supply through a drive output and/or brake output, as well as with the use of leakage power of the shaft system (e.g., friction) and/or inertia and/or centrifugal force. Braking, advantageously in the adjustment direction of “retarded” can also be realized under the full use or shared use of the friction power of the camshaft. A camshaft adjuster can be equipped with or without mechanical limiting of the adjustment range. As a gear drive in a camshaft adjuster, one-stage or multiple-stage triple-shaft gear drives and/or multiple links or coupling gears are used, for example, in structural form as a wobble-plate gear drive, eccentric gear drive, planetary gear drive, undulating gear drive, cam-plate gear drive, multiple-link or linked gear drive, or combinations of the individual structural forms in a multiple-stage construction.
For operation of the camshaft adjuster, a lubricant must be fed to lubricating positions, especially bearing positions and/or rolling toothed sections, wherein the lubricant is used for lubricating and/or cooling components of the camshaft adjuster that can move relative to each other. For this purpose, the camshaft adjuster has a lubricant circuit, which can be coupled, for example, with the lubricant circuit of the internal combustion engine.
From DE 696 06 613 T2 it is known that a control fluid for a camshaft adjuster with a vane-cell construction can contain impurities. If such impurities settle between vanes and a wall of a chamber defining an end position of the vane, this produces a change in the end position of the vane. This has the result that a maximum advanced or retarded state of the camshaft adjuster can no longer be reached exactly, which can make it impossible to control the valve timing as desired. In addition, impurities can get between the upper section of a vane and an outer peripheral wall of the chamber, which causes the control forces for actuating the camshaft adjuster to be increased and/or the fluid tightness between pressure chambers arranged on opposite sides of the vane becomes worse. This can lead to a decrease in the dynamic response of the camshaft adjuster.
Furthermore, it is known from DE 40 07 981 C2 to connect a damper, which is used for receiving or absorbing changes in rotational moment of the camshaft, between a belt pulley and a camshaft in a camshaft adjuster. Here, the damper can be formed as a viscosity damper, which includes annular labyrinth channels filled with a viscous fluid.